Medical catheters are widely used for percutaneous drainage of fluid from body cavities. For example, such catheters may be used in percutaneous nephrostomy, and for drainage of abscesses, bile, cysts, pleural effusions, empyemas, mediastinal collections and ascites. Percutaneously inserted catheters are also used as gastrostomy feeding tubes. In these and similar drainage and feeding applications, the catheters are typically inserted over a previously emplaced guide wire or by direct puncture and insertion using a trocar stylus. Once in position in the body cavity with the proximal end of the catheter protruding from the body, such catheters typically are anchored by forming and maintaining a restraining configuration at the distal end of the catheter in the shape of a pigtail, a J-curve, or a malecot rib. It is very advantageous to include a locking mechanism near the proximal end of the catheter for reliably locking and unlocking the distal restraining portion by manipulating a flexible filament that controls the restraining portion from an access point where the catheter protrudes from the body.
Many known catheter anchoring systems include flexible filaments like suture attached to the distal ends of the catheters to form and maintain the distal end of the catheters in a restraining configuration. Such catheter anchoring systems include locking mechanisms at the proximal ends of the catheters to releaseably hold the suture or other flexible filament in a desired drawn-up restraining position. Currently available locking mechanisms in these catheter anchoring systems comprise, for example, stopcock-type locking mechanisms, flexible sleeve configurations to cover and restrain the suture, locking bushings, and various complex clamping structures.
Prior catheter anchoring systems are described, for example, in U.S. Pat. Nos. 4,643,720 and 4,740,195. These anchoring systems use a stopcock feature to capture the suture that controls the restraining configuration of the catheter within the lumen of the catheter. The end of the suture exits the catheter directly through a proximal housing.
There are several problems associated with this system. First, in order to lock and unlock the system, the operator is required to use a special key device provided with the system. Unfortunately, when it comes time to remove the catheter, this key device may no longer be available and so the user will have to find a suitable tool that will properly function in lieu of the missing key device. Second, the positioning of the suture within the lumen of the housing is problematic. In particular, because the suture exits the proximal housing, it frequently ends up crossing the threaded interface between the catheter housing and the drainage device that the catheter is attached to. For example, when such catheters are attached to drainage collection bags, the presence of the suture across the threaded interface can cause leakage across the interface that is unpleasant for the patient and can create contamination risks for individuals who come in contact with the patient and/or the device.
Another commonly used catheter anchoring system is described in U.S. Pat. No. 5,399,165. This system utilizes a hinged lever with a cam feature to restrain the suture holding the restraining configuration of the catheter in place. Like the above device, this locking system cannot be unlocked without the use of a tool that needs to be identified and procured by the health care professional attempting to unlock the system.
The system of embodiments of the present invention requires no special tools for locking or unlocking. The user locks the system by moving a permanently mounted locking slide into a proximal position. To unlock the system, the user depresses a latch and moves the locking slide distally. Also, there is no leakage due to suture position since the free proximal control portion of the suture (flexible filament) that controls the restraining portion of the catheter exits the catheter lumen through a unique elastomeric cover positioned on the sidewall of the device and a seal sleeve which together ensure leakage-free operation. Also, since the suture does not pass through the proximal luer lock, it cannot interfere with the threaded interface to the collection device.
A prior art locking catheter system described in U.S. Pat. No. 5,522,400, assigned to the present assignee, is illustrated in FIG. 1. In this locking catheter system a flexible filament F passes through a compressible bushing B made of a conventional deformable sealing material like silicone. This bushing is disposed in a recess R in the housing of the device. When compressed, the bushing locks the flexible filament in place while maintaining a liquid and gas seal.
Another prior art locking catheter system believed to have been in the market since at least 1999 is sold under the SKATER® trademark by Angiotech Pharmaceutical (f.k.a. Medical Device Technologies, Inc.). A portion of the housing of this catheter is depicted in FIG. 2. As shown there, the housing of the SKATER catheter includes a seal recess R in the sidewall SW of the housing. A tube T is positioned in recess R and contains a deformable sealing material that fills the lumen of the tube. A flexible filament F passes through the deformable sealing material in order to limit system leakage as the suture passes through the recess.
Yet another catheter anchoring system is described in U.S. Pat. No. 7,217,256. A significant problem associated with this system, which is illustrated in FIG. 3, is that the deformable sealing material that is located in the sidewall recess of the device may not, in fact, reliably seal. As can be seen in FIG. 3, a flexible filament F passes through sealing material S which is confined in a seal recess R in a sidewall SW of the housing of the device. As in the case of the other prior art locking catheter systems discussed above, leakage experienced with this device will be problematic because it can be unpleasant for the patient and, more importantly it can also create contamination risks for individuals who come in contact with the patient or the device.
A medical device with a seal sleeve covering a port is shown in FIG. 4. This device is a urinary drainage bag having a sampling port P opening in the sidewall SW of the device and a piece of elastomeric tubing ET that fits over the port encircling and sealing the port when it is not in use. Sampling is carried out by passing a syringe needle through the tubing mounted over the port and withdrawing fluid. The elastomeric tubing maintains a seal against the syringe needle to prevent leakage. This device is believed to be first on market circa 1983.
Returning to FIG. 3, it is noted that the system of the '256 patent depicted there is also very difficult to unlock. To unlock the device, the user first needs to move a strain relief SR distally, which is difficult to accomplish because of the material of construction and the shape of the strain relief. Once the user moves the strain relief distally, he or she must simultaneously pry up the lock catch LC and move the slide SL distally. Given the size and shape of the lock catch, this maneuver is difficult and cumbersome to carry out.
In contrast, in the present catheter locking system, the user unlocks the system by simply depressing a latch and moving a locking slide distally which can be accomplished with one hand. Contoured surfaces on the locking slide make this maneuver particularly simple and efficient even when the user is wearing gloves and even if the gloves and slide surfaces are wet from bodily fluids.
Thus, prior art locking mechanisms are generally difficult to use. They are often less reliable than desired, may leak, and can be expensive to construct. Also, many have a high profile so that they stand away from the body and are inconvenient and uncomfortable to wear.
Additionally, many prior locking mechanisms lack a positive locking indication, leaving the physician uncertain as to whether or not the locking mechanism is fully and reliably engaged. Some prior locking mechanisms require a sealing compound to resist leakage from the catheter which may cause contamination or lead to failure of the seal. Finally, prior art locking mechanisms typically require two handed operation which make them unnecessarily difficult and cumbersome to use.
Embodiments of the present invention solve these problems by providing a flexible filament locking mechanism that is easy to assemble, economical to manufacture, has a low profile, can be manipulated between its locked and unlocked positions with one hand, and includes a positive indication of when it is locked. The locking mechanism of embodiments of the present invention, which may be used with or without a catheter, also accommodates a range of different flexible filament diameters. When used with the catheter described below, it provides a highly reliable seal without the use of sealing compounds to prevent leakage where the portion of the filament that controls the restraining portion of the catheter emerges from the catheter, and it includes a feature to facilitate storage of excess filament material when the filament is in its drawn-up restraining position.